Thanks EXP AIRCRAFT

[Alex D]

Walt, just wanted to thank you for a great job balancing my propeller.

Last Sunday took the RV7 up for a test flight and it is smooooooth!

Thanks Again
Alex
www.RVTraining.com

[Walt]

Thanks for the feedback Alex

When you fly the 10 you should definately notice the difference, it wasn't as bad as the 7 but the 6 cyl motors really benefit from balancing due to their inherently smoother operation.

[Bob Axsom]

Walt's process is reported to be better than the one I experienced at Hartzell. I am going through my 4 page annual condition inspection and I have now got the spinner off to inspect and lube the prop. I looked at the screw, nut and wiecht plate on the aft spinner bulkhead that was not checked for dynamic balance after installation for the purpose of dynamic balancing the system. It performs ok but I have a hard time believing in the actual results. Walt rechecks after the weight is added. I guess I would like to know Walt, what are your findings on the after balance check. If you have complete records - you know hard data - I would like to know the numbers.

Bob Axsom

[Walt]

Bob, I have hard numbers for every balance I do and provide that data to every customer. I'm not quite as computer savy as our host DR or I would post the actual plots, but here are the numbers for Alex's 7 & 10.

RV7: 4 Runs: .132, .048, .025. .035
RV10: 3 Runs: .069, .009, .014

Alex's aircraft were somewhat unique for RV's as they both had custom flywheels to support air conditioning so I had to drill and install weights on the spinner bulkheads on both aircraft. As you can see from the above numbers the final run with the single weight installed increased by .01 IPS for the RV7 and .05 for the RV10 (sometimes it goes down but you never know until you check). The final position/weight is calculated from the 2 weights temporarily installed on the spinner screws. When you change the radius and move them aft to the bulkhead things will change. I strive to keep the final IPS number less than .04 and I know when I calculate a move to the bulkhead there is the possibility for some error so I work to get the number a bit lower to allow for this.

When you can use the Lycoming flywheel to install weights its easier and more accurate to split the weights on the flywheel and easier to tweak.

When installing on the bulkhead I prefer to calculate a single weight positiion so you only drill a single hole, but this will always be a bit of a compromise as there is no way to tweak it (if someone really wanted to tweak it as low as possible then you could drill 2 positions on the bulkhead and split the weights). However, in reality once the balance is in the .03 IPS range or less you really aren't gaining much to go to .02 IPS.

Keep in mind that most Prop shops that do balancing call it quits when they get to .1 IPS which is the industry "standard" upper limit after balancing. Being that I'm self employed, not in a hurry, enjoy doing this and pride myself in precision I'm not personally satisfied until I've taken the time and have done the best job possible which means I don't quit until I have gotten to at least half the industry standard or less (usually less). My average balance generally ends up in the .025-.035 range but I do love it when I get them in the .014 range like we did on Alex's RV10

[Bob Axsom]

Physically you know there has to be some ... "difference" between the test weight test and the actual fixed weight test. I'm sure Hartzell focused on doing a good job - I was there participating - but the lack of final test after fixing the weight bugged me. Your information tells me that my ballance is probably OK but the lack of verification still bugs me in a procedural way.

Bob Axsom

[Louise Hose]

Walt,
I just wanted to add to the praise on your prop balances. I was on the oil spill and didn't have a chance to fly the -6 for awhile after the balance. When I did, I could notice a very nice improvement in the smoothness. Thanks!

[Walt]

Originally Posted by Bob Axsom

Physically you know there has to be some ... "difference" between the test weight test and the actual fixed weight test. I'm sure Hartzell focused on doing a good job - I was there participating - but the lack of final test after fixing the weight bugged me. Your information tells me that my ballance is probably OK but the lack of verification still bugs me in a procedural way.

Bob Axsom

You're "Probably" right, but honestly I would never even consider not doing a final confirmation run, it doesn't take much of a miscalculation to throw things way out. As you can see from the numbers above even doing a "perfect" mathmatical calculation it still changed on the final run.

Originally Posted by Louise Hose

Walt,
I just wanted to add to the praise on your prop balances. I was on the oil spill and didn't have a chance to fly the -6 for awhile after the balance. When I did, I could notice a very nice improvement in the smoothness. Thanks!

Thanks Louise, Paul still needs to bring his 8 up here so we can get it done

[Walt]

Here's a good reason to get your vibration checked, had this one drop in today and the owner just had the prop redone by a local prop shop and he thought it had "a little" more vibration than it used to. Vibs were 1.45 IPS (upper limit is 0.2 IPS).

This was the first time I'd ever seen one this high and it set off an alarm on the balancer to immediately warn the operator (Danger Will Robinson).

Basically this aircraft was in an unsafe condition to fly and I told the owner he needed to immediately remove the prop and return it to the shop to have the static balance checked. He told me that the static weights that used to be on the prop were not there when he got it back after rework and he thought that was unusual, but he installed it anyway, bad move (he is an A&P also).

Note the small red circle in the middle is the upper limit after balance of 0.1 IPS.

[flyindoorman]

Walt

If i fly my RV10 up to Ft Worth about what is the cost for doing a prop balance ?

[Walt]

Cost is $150 for my all VAF RV friends

More info on my website.